Vapor Phase Mass Transfer in Partially-Saturated Porous Media
Public Deposited- Last Modified
- February 27, 2019
- Creator
-
Corn, Fredrick E.
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
- Abstract
- Sampling of the partially-saturated zone at the site of regular, long-term dumping and burning of jet fuels revealed vapor-phase concentrations of volatile organic compounds up-gradient from the point of dumping. This suggests that significant amounts of volatile compounds may be transported through the partially-saturated zone by vapor-phase diffusion. The laboratory component of this research examined both the steady-state and transient diffusion behavior of toluene, a volatile organic compound, in 6-cm long columns packed with glass beads and soil. One end of a column was exposed to toluene vapor and the other was sampled periodically using an activated carbon trap. The results of these diffusion experiments, when compared to column diffusion simulated with a one-dimensional finite difference model, revealed a retardation effect during the approach to steady state. The retardation effect was attributed to vapor-aqueous and aqueous-solid phase partitioning. Linear sorption constants were determined for the experimental data using the finite difference model. Although there was some variability in the data from one set of column runs to another, one set of experiments run with soil at 50-70% of saturation, was closely approximated using a linear sorption coefficient consistent with the linear coefficient found for a saturated system in an independent batch experiment. Sorption parameters for the saturated system were determined with a bottle-point equilibrium study and a non-linear Freundlich sorption model was found to describe the saturated system more accurately than a linear model. For several of the diffusion columns however, the model, run with linear sorption parameters, predicted transient diffusion behavior that fit the experimental data well.
- Date of publication
- May 1989
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Miller, Cass T.
- Harris, Robert L.
- DiGiano, Francis A.
- Degree
- Master of Science in Environmental Engineering
- Academic concentration
- Industrial Hygiene
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 1989
- Language
- Deposit record
- ad7e9272-7c4f-43e0-afeb-7a5f2526ad76
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